Adding another / additional web parts fails??? Any fix?

I observed that whenever I try to add additional web parts to the web parts solution even though the solution deploys properly, importing that particular additional web part fails. I tried it with multiple projects, multiple times assuming I was making
a mistake but things are so simple that I am sure I was not making any mistake atleast not everytime. $0$0If I rename the existing 2 web parts (customwebpart1 and customwebpart2) they are working fine but adding another class / .webpart and updating the feature/webparts.xml
is not successful. $0$0When I try to add the web part, it just throws the 'unable to import the web part' error which we specify in the .webpart file. I disabled the custom error and the error I get is as follows when I try to preview the web part from the
web part gallery. $0$0Error importing Web Part at Microsoft.SharePoint.WebPartPages.WebPartImporter.CreateWebPart(Boolean clearConnections) $0 at Microsoft.SharePoint.WebPartPages.WebPartImporter.Import(SPWebPartManager manager, XmlReader reader, Boolean
clearConnections, Uri webPartPageUri, SPWeb spWeb) $0 at Microsoft.SharePoint.WebPartPages.WebPartPreview.get_WebPart() $0 at Microsoft.SharePoint.WebPartPages.WebPartPreview.CreateChildControls() $0 at System.Web.UI.Control.EnsureChildControls() $0$0
at System.Web.UI.Control.PreRenderRecursiveInternal() $0$0 at System.Web.UI.Control.PreRenderRecursiveInternal()$0 at System.Web.UI.Control.PreRenderRecursiveInternal() $0 at System.Web.UI.Control.PreRenderRecursiveInternal() $0 at System.Web.UI.Control.PreRenderRecursiveInternal() $0
at System.Web.UI.Control.PreRenderRecursiveInternal() $0 at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)